issue #2243 -- prefer f-strings over %-interpolation

edited docs to prefer f-strings, then str.format(), and remove %-interpolation

additional ad-hoc documentation fixes, as opportunities seen:
- replace Built-In Function (BIF) "min" variable with "mins"
- prefer BIF str(var) over "%s" % var
- reformat some code examples to clarify multiple args passed to functions
- change some single-quote strings to double-quotes for consistency
- fix mismatched parens

misc edits:
- add .vscode/ to gitignore

docs/source/Concepts/Custom-Protocols.md

@@ -79,7 +79,7 @@ This is how it looks:
          if not MYPROC_ENABLED:
              return
          # output to list this with the other services at startup
-         print("  myproc: %s" % MY_PORT)
+         print(f"  myproc: {MY_PORT}")
 
          # some setup (simple example)
          factory = MyOwnFactory()